March 2015 Microphoto of the Month
Partially altered mineral, Mid-Atlantic Ridge
As seawater penetrated fractures in this mineral (clinopyroxene) the parts of the mineral near the fractures began to react with the water to form a different mineral (amphibole). Note that many of the fractures are vertical in this view. These are natural planes of weakness in the clinopyroxene (cleavage planes). Plane polarized light. Field of view 3 mm.